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Invertebrates I 12-1: Introduction to Animals 12-2: Sponges & Cnidarians 12-3: Flatworms & Roundworms
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12-1: Introduction to Animals Animals are extremely diverse, but they have basic characteristics in common
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Animal Characteristics Multicellular – made of more than one cell Eukaryotes – cells contain a nucleus Heterotrophic – feed off other organisms; consumers Reproduce sexually – Although some can reproduce asexually
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Animals have different adaptations that help them survive – Adaptations for obtaining energy some only eat plants (____________) – Example: deer, mice, some fish some only eat other animals (__________) – Example: hawks, lions, sharks some eat plants & animals (____________) – Example: humans, bears, raccoons some eat decaying matter called detritus (_________________) – Example: beetles, millipedes herbivores carnivores omnivores detritivores
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– Physical adaptations Protective coverings protect them from predators – Examples: shells & quills Size is also a defense Mimicry or camouflage
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– Camouflage helps predators also tigers & killer whales
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– Behavioral adaptations Some animals use chemicals to discourage predators Speed allows some animals to outrun predators Traveling in groups helps both predators & prey
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Animals are classified based on similarities they have in common – 2 major groups of animals depending on whether or not they have a backbone Invertebrates— Vertebrates— no backbone backbone
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– Symmetry how their body parts are arranged Asymmetrical – Animals do not have a definite shape Radial – Parts arranged in a circle around a center point Bilateral – Halves that are nearly mirror images
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12-2: Sponges & Cnidarians Sponges are invertebrates – Sponges have little in common with other animals—probably evolved separately from all other animals
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– Most are asymmetrical and sessile (do not move around; stuck to the ground) Sponge body is a hollow tube with one opening at the top (osculum) and many small pores along the body tube osculum pores
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No tissues, organs, or organ systems; very simple Have spicules for protection and support
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Filter feeders – they pull food and oxygen through their pores and expel wastes through the osculum Most are hermaphrodites – produce both sperm and eggs
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Can also reproduce asexually by budding and regeneration
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Cnidarians – invertebrate animals that include corals, sea anemones, jellyfish, hydras, and Portuguese man-of-wars
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– Most have 2 body forms Polyp—vase shaped and sessile Medusa—bell-shaped and free swimming
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– Have one body opening and symmetry – Have cell layers arranged into tissues radial
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– Have a digestive cavity to break down food – Have a system of nerve cells called a nerve net connects all parts of the organism; allows them to sense and respond to the environment
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– Have tentacles with stinging cells that surround the mouth – They are predators
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– Reproduce sexually and asexually
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Most cnidarians fossils are corals Reefs form as corals secrete hard skeletons on those of earlier generations
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– It takes millions of years for large reefs to form – Reefs are important ecosystems provide shelter for many organisms protects shorelines from erosion some corals produce chemicals that are used in medicines
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12-3: Flatworms & Roundworms Worms are invertebrates – soft bodies; circular shape – symmetry – different layers; gives them organs and organ systems bilateral
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Flatworms – first to evolve bilateral symmetry – start to have different tissues – usually parasites – some free-living – some have mouths
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– Planarians free-living; feed on small organisms or dead bodies triangular shaped head with eyespots bodies covered with cilia and they produce mucous eyespots
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usually live under rocks, on plant material, or in fresh water can reproduce asexually by fission or sexually; lay eggs
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– Flukes parasites; life cycle requires more than one host reproduce sexually; male fertilizes female and she lays eggs can infect lungs, liver, eyes, and other organs
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– Tapeworms parasites; uses hooks and sucker to attach to hosts’ intestines don’t have digestive tract body is segmented, and as it grows it adds more segments hermaphrodites that fertilize themselves
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Roundworms – called nematodes – more complex than flatworms – have two body openings—mouth and anus – live almost everywhere!!!
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– most have separate male and females that reproduce sexually – many are plant and animal parasites (heartworms) – some are helpful—kill pests (termites, fleas, ants, etc.) – also helpful in enriching soil
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